Cassette and analyzer device

ABSTRACT

A cassette for loading into a bay of an analyzer device, the cassette having a supply chamber for a test tape, an uptake chamber to receive used tape and a test zone between the chambers, where the tape is positioned at a test site for testing purposes, wherein the cassette includes a frame that extends across the test zone on a loading side of the tape, the frame being in a protective position relative to the tape, parallel to and aligned with the tape in the test zone, to protect the tape as the cassette is inserted into the bay of the analyzer device.

RELATED APPLICATIONS

This application claims priority from Australian Patent ApplicationNumber 2012904135, Australian Patent Application Number 2012904710 andAustralian Patent Application No. 2013901667, the contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a cassette for holding a carrier tapewith test elements and aspects of loading the cassette into an analyzerdevice.

BACKGROUND OF THE INVENTION

Body fluid samples such as blood, plasma, urine, interstitial fluid,etc, may be analyzed for various components or properties, such asglucose, cholesterol, pathogens, drugs of abuse, coagulation,hematocrit, etc. The body fluid sample is applied to a test elementcontaining reactive ingredients. A reaction occurs and a result isproduced. An instrument may be required to read the result or the resultmay be interpreted by eye by, for example, colour matching or symbolssuch as bars, dots, etc.

The test elements may be supplied in multiple numbers along a carriertape housed in a cassette. The test cassette is provided with twochambers, a sealed supply chamber containing the tape with unused testelements and an uptake chamber for storage of the tape with used testelements. The test cassette can be used in a laboratory analyzer or aportable analyzer.

Loading the cassette into the analyzer can be problematic for a numberof reasons. A sensor head of the analyzer is usually required to comeinto contact with the tape and test element. In the case of biosensors,the sensor head needs to make electrical connection and, in the case ofa photometric test, the test element needs to be positioned at a fixeddistance from the analyzer optics. As such, the tape needs to bereliably held at a specific test site, relative to the sensor head.

U.S. Pat. No. 7,378,270 (Roobik, et al) discloses a cassette that isinserted into an analyzer, whereupon a sensor head of the analyzer ismoved forward into contact with the tape. The moveable head complicatesconstruction and is not ideal for low cost hand held analyzers.

Another solution involves placing the tape over a sensor head manually.This requires the cassette to be manipulated into a position to placethe tape onto the sensor head prior to insertion of the cassette intothe analyzer. This approach may be suitable for a trained technician butnot an unskilled user.

Even when the tape is properly loaded into an analyzer, there may be aproblem with a new test element being drawn out of the supply chamber byinadvertent activation of a drive wheel.

If a new test element is inadvertently pulled out of the supply chamberearly, the test element will be prematurely exposed to ambientconditions, which may adversely affect the reagents on the test element.For example, the test elements may be exposed to humidity, which canadversely affect the performance of the test.

If a test element is only partially pulled out of the supply chamber,the seal of the supply chamber may be compromised. This can allowmoisture to enter the supply chamber. As the test elements are generallyhydrophilic, this can damage all the tests in the chamber.

As such, it is desirable to prevent inadvertent activation of the drivewheel unless a test is ready to be undertaken.

OBJECT OF THE INVENTION

The present invention seeks to address or ameliorate at least one of theabove problems.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, there is provided acassette for loading into a bay of an analyzer device, the cassettehaving a supply chamber for a test tape, an uptake chamber to receiveused tape and a test zone between the chambers, where the tape ispositioned at a test site for testing purposes, wherein the cassetteincludes a frame that extends across the test zone on a loading side ofthe tape, the frame being in a protective position relative to the tape,parallel to and aligned with the tape in the test zone, to protect thetape as the cassette is inserted into the bay of the analyzer device.

Preferably, the frame includes guides that direct the tape from thesupply chamber to the test zone and away from the test zone to theuptake chamber, and a bridge portion that extends between the guides toprotect the tape across the test zone.

Preferably, the cassette includes a biasing element to deflect thecassette into a loaded position when the tape is presented to the testsite of the analyzer device, the biasing element causing a housing ofthe cassette to be displaced in order to move the frame away from theprotective position relative to the tape and to leave the tape tensionedacross the test site.

Preferably, the biasing element engages with structure of the analyzer,to bias the frame into a receiving recess of the analyzer.

Preferably, the cassette includes at least one catch at a rear end ofthe cassette remote from the test zone, to lock a rear end of thehousing into the bay.

Preferably, the supply chamber includes a supply spool and the uptakechamber includes an uptake spool wherein the supply spool is mounted ona fixed axis internally of the supply chamber and the uptake spool ismounted on a floating axis adapted to slide relative to the housing ofthe cassette.

In another aspect, there is provided an analyzer device with a bay forreceiving the cassette, as described above, and a test site provided onstructure that projects into the test zone of the cassette, thestructure including a recess, between a floor of the bay and the testsite, to receive the frame of the cassette, when the cassette is loadedinto the bay.

Preferably, the device includes at least one latch toward an end of thebay, to anchor a rear end of the cassette during a loading operation,when the cassette is moved rearward during insertion into the bay.

Preferably, the structure includes an angled surface against which thebiasing element of the cassette engages as the cassette moves into theloaded position to translate the housing rearward, in order to lock therear of the cassette in the bay and draw the frame into the recess.

Preferably, the structure is in the form of a pillar with a reading headon a front side and a wedge profile on a rear side.

Preferably, the front side and rear side of the pillar are separated bya distance sufficient to energize the biasing element against the rearside and cause the frame to engage with and slide down the front side ofthe pillar as the cassette is moved into the loaded condition.

In yet another aspect, there is provided an analyzer device and testcassette combination, wherein:

the cassette includes a housing with a supply chamber for holding a tapewith test elements, an uptake chamber for storing used tape and a testzone where the tape is presented for testing;

the device includes a bay with a floor and structure with a test sitearranged to project into the test zone when the cassette is loaded intothe device; the cassette including a frame located between the chambersand adjacent the tape on an insertion side of the tape, to protect thetape as the tape is fitted laterally over the test site; and wherein

the cassette is moved in a lengthwise direction during a final stage ofloading so as to displace the frame laterally of the test site while thetape remains over the test site.

Preferably, the device includes a capstan that is received in the uptakespool, wherein the capstan is arranged to rotate on a fixed axis and theuptake spool is arranged to rotate on a floating axis so as to bedisplaced laterally of the housing of the cassette and accommodaterelative movement of the capstan, when the cassette is displacedlengthwise during loading.

The device may include a manual or motor drive means of rotating thecapstan. Optionally, the device includes a drive wheel coupled to theuptake spool for advancing the tape to the test site and a lockmechanism to selectively prevent the drive wheel engaging and drivingthe uptake spool. The lock mechanism may also be used with the motordriven version.

Preferably, the device includes a moveable cover over the test site andthe lock mechanism is disengaged as a result of the cover being moved toan open position.

Preferably, the lock mechanism includes a lever that is biased intoengagement with the drive wheel, to prevent rotation of the drive wheel,and a lug associated with the cover, that moves in response to movementof the cover, to shift the lever into a disengaged position when thecover is opened.

In yet another aspect, there is provided a cassette with a supplychamber that houses a supply spool and an uptake chamber that houses anuptake spool, arranged whereby to hold a tape that passes between thesupply spool and the uptake spool, wherein the supply chamber houses thesupply spool in a sealed environment and the uptake spool rotates on ana floating axis and is accessible for driving engagement through anopening in a base of the cassette.

Preferably, the floating axis allows the uptake spool to slide laterallyinside a housing of the cassette in order to accommodate relativemovement of a capstan that is used to drive the uptake spool.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is more fully described, by way of a non-limiting exampleonly, with reference to the accompanying drawings, in which:

FIG. 1 is a top view of a cassette shell;

FIG. 2 is a bottom view of a cassette;

FIG. 3 is a perspective view of a front of the cassette;

FIG. 4 is a perspective view of a back of an analyzer device;

FIG. 5 is a perspective view of a cassette loaded into the device;

FIG. 6 is a partial cross-sectional view of the cassette and device;

FIG. 7 is an elevated perspective view of the back of the device;

FIG. 8 is a plan view of the back of the device;

FIG. 9 is a perspective view of a rear of the cassette;

FIG. 10 is a bottom perspective view of the cassette;

FIG. 11 is a bottom view of the cassette, illustrating displacement of atake-up spool;

FIG. 12 is a perspective cross-sectional view of the cassette;

FIG. 13 is a front view of the device;

FIG. 14 is a top front perspective view of the device, without a coverplate, illustrating an interior of the device;

FIG. 15 is a front view of the interior of the device;

FIG. 16 is a front view of the interior of the device, illustrating alock mechanism in a release condition;

FIG. 17 is a top perspective view of the device of FIG. 16, with thelock mechanism in the release condition; and

FIG. 18 illustrates insertion of the cassette into the analyzer device.

DETAILED DESCRIPTION OF THE INVENTION

Referring firstly to FIG. 1, part of a cassette 1 is shown in the formof a shell 2 that includes a body 3 with a supply spool 4 and a uptakespool 5. A tape 6 extends from the supply spool 4, through a test zone 7and onto the uptake spool 5.

The supply spool 4 is located in a supply chamber 8 that is defined by afront wall 9, a back wall 10 and a side wall 11. A further side wall 12serves to close the chamber 8. The wall 12 is secured to the back wall10 and projects past an end 13 of the front wall 9 so as to define asmall gap 14 between the wall 12 and the front wall 9, for the tape 6 toexit the chamber 8.

An elongate finger 15 projects from the front wall 9 and the Wall 12 isarranged to sit in close proximity to the finger 15 to maintain a seal16 against the tape 6, as the tape 6 is drawn through a channel 17between the wall 12 and finger 15. The finger 15 terminates in a guide18 that is angled toward the test zone 7, to direct the tape 6 to thetest zone 7, where a test element 19 is located for testing.

A corresponding guide 20 is positioned on an opposite side of the testzone 7 for directing used tape 6 back down the side wall 11, over abrake 21 (that keeps the tape in tension across the test zone 7) andonto the uptake spool 5.

Referring to FIG. 2, the cassette shell 2 is shown fitted into a housing22 to form the completed cassette 1. The housing 22 is snap-fitted ontothe shell 2 using clips 23 so that a base 24 of the housing 22 at leastpartially closes over the uptake spool 5 and a circular opening 25 isprovided to allow access to the spool 5.

The base 24 includes side extensions 26 that overlay the guides 18, 20.A bridge portion 27 extends between the guides 18, 20 to form a frame 30that aligns with the tape 6, shown in dashed lines. A biasing element 31projects from the base 24 into a free space 32 adjacent the test zone 7.

Referring now to FIG. 3, the tape 6 is illustrated as being tensionedbetween the guides 18, 20, parallel to and laterally adjacent the frame30 so that the bridge portion 27 is in a protective position relative tothe tape 6. The frame 30 thereby protects the tape 6 laterally, on aloading side 28, from damage or kinking. The frame 30 is shown asforming a window 33 in front of the tape 6, so that blood or othermaterial for testing can be deposited on the tape 6.

Referring now to FIG. 4, an analyzer device 40 is illustrated asincluding a main body 41 with a recessed bay 42 with a curved inner end43 and an open outer end 44. Structure 45 projects upwardly from a floor46 of the bay 42, adjacent the outer end 44 of the bay 42. The structure45 includes a post 47 with a sensor head 48 that defines a test site 49on a front side 50 and a recess 51 at a lower end 52 of the post 47. Anangled surface 53 is provided in the form of a wedge profile 54 on arear 55 of the structure 45.

A capstan 56 projects up from the floor 46, toward the inner end 43 ofthe bay 42. The capstan 56 is designed to fit in the uptake spool 5 andthe structure 45 is designed to be received in the test zone 7 of thecassette 1, when the cassette 1 is loaded in the bay 42 of the device40, as shown in FIG. 5, where the frame 30 is shown clipped down overthe sensor head 48 and into the recess 51, to lock the cassette 1 inplace.

With reference to FIG. 6, the capstan 56 is shown connected to a gearmechanism 57 to rotate around a fixed axis 58. The gear mechanism 57includes a drive wheel 59 and an input gear 60. A lock mechanism 61 thatincludes a lever 62 is provided to engage teeth 63 of the drive wheel 59and thereby prevent rotation of the drive wheel 59.

FIG. 6 also clearly shows the angled surface 53, behind the sensor head48, as being wedge shaped and tapered rearward, toward the floor 46 ofthe bay 42. The recess 51 at the lower end 52 of the post 47 is definedunderneath a forward nose portion 64 of the post 47.

Referring to FIGS. 7 and 8, the device 40 also includes a slide cover70, shown in the open position, where the sensor head 48 is exposed fortesting purposes. In that arrangement, the lock mechanism 61 (as shownin FIG. 6) is disengaged to allow the capstan 56 to be rotated underaction of a thumb wheel 71.

The bay 42 also includes two latches 72 at the inner end 43 of the bay42, adjacent the floor 46. The latches 72 have a sloped upper deck 73and an undercut ledge 74. The angled surface 53 is provided from a topsurface 75 of the post 47 and continues down onto spaced apart wedgeprofiles 54 that are substantially in alignment with the latches 72 atthe inner end 43 of the bay 42.

Turning now to FIG. 9, a rear lower edge 76 of the cassette 1 isprovided with two catches 77 that are each formed with a bevelled edge78 and an upper ledge 79. During movement of the cassette 1 into thedevice 40 of FIG. 7, in an insertion direction indicated by arrow “D”,the bevelled edge 78 of each catch 77 is designed to engage with thesloped upper deck 73 of the latches 72. This has the effect of forcingthe cassette 1 in an initial forward direction “F” to ensure the frame30 clears the structure 45 at the outer end 44 of the bay 42, whilstprotecting the tape 6 from lateral engagement or damage from thestructure 45.

After the bevelled edges 78 clear the respective upper decks 73, theupper ledges 79 slide under the undercut ledges 74, in a rearwarddirection “R”, to lock a rear end 80 of the cassette 1 into the device40.

Referring to FIG. 10, the biasing element 31 is positioned to abut thewedge profile 54 at the rear 55 of the structure 45 (as shown in FIG.8), when the frame 30 extends over the sensor head 48. As the cassette 1is moved in the insertion direction “D”, the frame 30 is forced downover the structure 45 which energizes the biasing element 31 and causesthe frame to resiliently engage the post 47, until the bridge portion 27is biased into the recess 51 on the post 47, which then allows thecassette 1 to be urged in the rearward direction “R” to thereby lock thecatches 77 under the latches 72. This action causes the tape 6 to betensioned across the test site 49, over the sensor head 48. As may beappreciated, during movement of the cassette 1 in the insertiondirection “D”, the tape 6 is protected from sideward engagement with thesensor head 48 by the frame 30, which prevents damage to the tape 6.

The entire process of loading the cassette 1 into the device 40 isillustrated in the schematic drawings of FIG. 18.

In particular, FIG. 18 a shows the cassette 1 being moved in theinsertion direction “D”. FIG. 18 b illustrates the frame 30 being urgedin the forward direction “F”, as movement of the cassette continues inthe direction “D”. Forward movement of the frame 30 is effected by acombination of the resilient engagement with the structure 45 and thecassette 1 engaging the latches 72.

In FIG. 18 c, the capstan 56 has been received in the uptake spool 5 andthe action of the biasing element 31 on the structure 45 urges thecassette 1 in the rearward direction “R”, such that the frame 30 issnapped into the recess 51. FIG. 18 d shows the cassette 1 in the fullyloaded condition.

Referring now to FIG. 11, the relative position of the uptake spool 5within the cassette during the loading operation is described in moredetail. The uptake spool 5 is shown laterally displaced toward the rearend 80 of the cassette 1. This is the position the spool 5 needs toadopt to engage the capstan 56 during the initial insertion of thecassette 1 into the bay 42 of the device 40. Since the capstan 56 isarranged to rotate on a fixed axis 58, the uptake spool 5 needs to beable to float relative to the capstan 56, as the cassette housing 22moves relative to the capstan 56 during insertion. In particular, thecassette 1 initially slides in the forward direction “F” and then backin the rearward direction “R” during insertion into the device 40.

With regard to FIG. 12, the uptake spool 5 is allowed to float by simplybeing housed in an uptake chamber 82, which is defined between the base24 and a lid 83 of the cassette 1. As such, the uptake spool 5 is freeto float by sliding lengthwise of the uptake chamber 82 and cassette 1,as needed. The supply spool 4, on the other hand, is mounted on a hub 84that is sealed within the supply chamber 8, to rotate on a fixed axis85.

Since the uptake spool 5 is free to move lengthwise of the housing 22,the spool 5 does not present a reliable mechanism for maintainingtension on the tape 6 when the cassette 1 is out of the analyzer device40. As such, a separate and independent mechanism is used to maintaintension on the tape 6, in the form of the brake 21, described withreference to FIG. 1. The brake 21 is preferably an integrally mouldedpart of the housing 22, positioned between the test zone 7 and theuptake spool 5. The brake 21 is formed of thermoplastic elasticmaterial, to grip the tape against the housing 22 and maintain tensionof the tape 6 across the test zone 7, thereby allowing the spool to movefreely when our of the analyzer 40.

Referring to FIG. 13, the device 40 has a power button 86, a testfunction button 87 and a screen 88 for displaying a test result. Thedevice 40 is shown with the slide cover 70 in a closed position, whichlocks the thumb wheel 71 against rotation, or at least prevents the tape6 from being wound forward by the wheel 71, even in the event the wheelis turned.

Referring to FIG. 14, the thumb wheel 71 is shown connected to the inputgear 60, which meshes with the teeth 63 of the drive wheel 59. The lever62 is mounted on a boss 89 and a resilient member 90 holds the lever inengagement with the drive wheel 59. The thumb wheel 71 is therebyprevented from rotating the drive wheel 59. A clutch device 91 may beprovided to allow free rotation of the thumb wheel 71 until the lever 62is released.

Referring now to FIG. 15, the slide cover 70 is attached to a tail 92that is constrained to slide along an elongated track 93 in a side 94 ofthe device 40. The tail 92 has a lug 95 arranged to engage the lever 62when the slide cover 70 is opened.

With reference to FIG. 16, the slide cover 70 is shown in an openposition, where the lug 95 has engaged the lever 62 and pivoted thelever 62 against the resistance of the resilient member 90, to allowrotation of the drive wheel 59. In that position, the thumb wheel 71 canbe rotated to advance the tape 6 across the sensor head 48 to present anew test element 19 to the test site 49.

With regard to FIG. 17, the slide cover 70 is again shown in an openposition in which the tape 6 is shown tensioned between the guides 18,20 so that the test element 19 is located over the sensor head 48. Thisallows a sample of blood or other material to be deposited on the testelement 19 for testing purposes. When the test has been completed, thetape 6 can be advanced by rotating the thumb wheel 71, which engages thedrive wheel 59 to wind the used test element 19 into the uptake chamber82 and index a fresh test element 19 out of the supply chamber 8 andonto the test site 49.

If testing is complete, the cover 70 can be slid back into the closedposition, to engage the lock mechanism 61 in order to secure the drivewheel 59 from further rotation. As such, the tape 6 is prevented frombeing inadvertently drawn out of the supply chamber 8.

It should be appreciated from the above that the cassette 1 allows thetape 6 to be reliably fixed over a test site 49, without damage fromlateral loading over the sensor head 48. Since the cassette 1 isdisplaced longitudinally and rearward during insertion, the tape 6 istensioned over the test site 49 such as to provide close proximity andcontact between the tape 6 and the sensor head 48, if needed. To removethe cassette 1, the housing 22 is simply pressed in a forward direction,against the resistance of biasing element 31, which causes the cassette1 to lift upwardly on the angled surface 53 of the structure 45 and awayfrom the floor 46 of the bay 42. As such, the cassette 1 may be easilyand reliably swapped in and out of the device 40. By using the cassette1, the tape 6 is automatically loaded onto the sensor head 48, withoutrequiring a skilled technician to separately load the tape onto the testsite 49.

LIST OF PARTS

-   1. Cassette-   2. Shell-   3. Body-   4. Supply spool-   5. Uptake spool-   6. Tape-   7. Test zone-   8. Supply chamber-   9. Front wall-   10. Back wall-   11. Side wall-   12. Side wall-   13. End-   14. Gap-   15. Finger-   16. Seal-   17. Channel-   18. Guide-   19. Test element-   20. Guide-   21. Spacer-   22. Housing-   23. Clips-   24. Base-   25. Opening-   26. Side extensions-   27. Bridge portion-   28. Loading side-   30. Frame-   31. Biasing element-   32. Space-   33. Window-   40. Analyzer device-   41. Body-   42. Bay-   43. Inner end-   44. Outer end-   45. Structure-   46. Floor-   47. Post-   48. Sensor head-   49. Test site-   50. Front side-   51. Recess-   52. Lower end-   53. Angled surface-   54. Wedge profile-   55. Rear-   56. Capstan-   57. Gear mechanism-   58. Fixed axis-   59. Drive wheel-   60. Input gear-   61. Lock mechanism-   62. Lever-   63. Teeth-   70. Cover-   71. Wheel-   72. Latch-   73. Upper deck-   74. Ledge-   75. Surface-   76. Lower edge-   77. Catch-   78. Bevelled edge-   79. Upper ledge-   80. Rear end-   82. Uptake chamber-   83. Lid-   84. Hub-   85. Fixed axis-   86. Power button-   87. Test button-   88. Screen-   89. Boss-   90. Resilient member-   91. Clutch device-   92. Tail-   93. Track-   94. Side-   95. Lug

1. A cassette for loading into a bay of an analyser device, the cassettehaving a supply chamber for a test tape, an uptake chamber to receiveused tape and a test zone at a forward end of the cassette, where thetape is positioned for presentation to a test site when loaded into theanalyser device, wherein: the cassette includes a frame that extendsalong one side of the test zone, on a loading side of the tape, theframe being laterally adjacent the tape and projecting forwardly of thetape and the test zone so as to protect a lateral edge of the tape asthe cassette is loaded into the bay of the analyser device.
 2. Thecassette of claim 1, further including guides that direct the tape fromthe supply chamber to the test zone and away from the test zone to theuptake chamber, and the frame includes a bridge portion that projectsforwardly and laterally of the guides, the bridge portion furtherdefining a window forward of the test zone.
 3. The cassette of claim 1,wherein the cassette includes a biasing element to deflect the cassetteinto a loaded position when the tape is presented to the test site ofthe analyser device, the biasing element causing a housing of thecassette to be displaced whereby the frame moves rearward relative tothe test site, while the test site and tape are advanced forwardrelative to the housing, to a position where a sample is able to bedeposited on the tape for testing.
 4. The cassette of claim 3, whereinthe biasing element engages with structure of the analyzer, to bias theframe into a receiving recess of the analyzer.
 5. The cassette of claim4, wherein the cassette includes at least one catch at a rear end of thecassette remote from the test zone, to lock the rear end of the housinginto the bay.
 6. The cassette of claim 1, wherein the supply chamberincludes a supply spool and the uptake chamber includes an uptake spoolwherein the supply spool is mounted on a fixed axis internally of thesupply chamber and the uptake spool is mounted on a floating axisadapted to slide relative to the housing of the cassette.
 7. Thecassette of claim 6, further including a brake to grip the tape againstthe housing and maintain tension in the tape across the test zone,whilst allowing the uptake spool to slide relative to the housing. 8.The cassette of claim 7, wherein the brake is formed integrally with thehousing from a thermoplastic elastic material, to grip the tape betweenthe test zone and the uptake spool
 9. An analyzer device with a bay forreceiving the cassette of claim 1, and a test site provided on structurethat projects into the test zone of the cassette, the section includinga recess, between a floor of the bay and the test site, to receive theframe of the cassette, when the cassette is loaded into the bay.
 10. Theanalyzer device of claim 9, wherein the device includes at least onelatch toward an end of the bay, to anchor a rear end of the cassetteduring a loading operation, when the cassette is moved rearward duringinsertion into the bay, in order for the at least one catch to lock withthe at least one latch.
 11. The analyzer device of claim 10, wherein thestructure includes an angled surface against which the biasing elementof the cassette engages as the cassette moves into the loaded positionto translate the housing rearward, in order to lock the rear of thecassette in the bay and draw the frame into the recess.
 12. The analyzerdevice of claim 11, wherein the structure is in the form of a pillarwith a reading head on a front side and a wedge profile on a rear side.13. The analyzer device of claim 12, wherein the front side and rearside of the pillar are separated by a distance sufficient to energizethe biasing element against the rear side and cause the frame to engagewith and slide down the front side of the pillar as the cassette ismoved into the loaded condition.
 14. The analyzer device of claim 9,wherein the device includes a drive wheel for advancing the tape in thecassette to the test site and a lock mechanism to selectively preventthe drive wheel from driving the tape.
 15. The analyzer device of claim14, wherein the device includes a moveable cover over the test site andthe lock mechanism is disengaged as a result of the cover being moved toan open position.
 16. The analyzer device of claim 15, wherein the lockmechanism includes a lever that is biased into engagement with the drivewheel, to prevent rotation of the drive wheel, and a trigger associatedwith the cover, that moves in response to movement of the cover, toshift the lever into a disengaged position when the cover is opened. 17.An analyzer device and cassette combination, wherein: the cassetteincludes a housing with a supply chamber for holding a tape with testelements, an uptake chamber for storing used tape and a test zone wherethe tape is presented for testing; the device includes a bay with afloor and a raised section with a test site arranged to project into thetest zone when the cassette is loaded into the device; the cassetteincluding a frame located between the chambers and adjacent the tape onan insertion side of the tape, to protect the tape as the tape is fittedlaterally over the test site; and wherein the cassette is moved in alengthwise direction during a final stage of loading so as to displacethe frame laterally of the test site while the tape remains over thetest site.
 18. The analyzer device and cassette of claim 17, wherein thedevice includes a capstan that is received in the uptake spool, whereinthe capstan is arranged to rotate on a fixed axis and the uptake spoolis arranged to rotate on a floating axis so as to be displaced laterallyof the housing of the cassette and accommodate relative movement of thecapstan, when the cassette is displaced lengthwise during loading. 19.The analyzer device and cassette of claim 18, wherein the deviceincludes a drive wheel coupled to the uptake spool for advancing thetape to the test site and a lock mechanism to selectively prevent thedrive wheel engaging and driving the uptake spool.
 20. The analyzerdevice and cassette of claim 19, wherein the device includes a moveablecover over the test site and the lock mechanism is disengaged as aresult of the cover being moved to an open position.
 21. The analyzerdevice and cassette of claim 20, wherein the lock mechanism includes alever that is biased into engagement with the drive wheel, to preventrotation of the drive wheel, and a trigger associated with the cover,that moves in response to movement of the cover, to shift the lever intoa disengaged position when the cover is opened.
 22. A cassette with asupply chamber that houses a supply spool and an uptake chamber thathouses an uptake spool, arranged whereby to hold a tape that passesbetween the supply spool and the uptake spool, wherein the supplychamber houses the supply spool in a sealed environment and the supplyspool rotates on an a floating axis and is accessible for drivingengagement through an opening in a base of the cassette.
 23. Thecassette of claim 22, wherein the floating axis allows the uptake spoolto move laterally inside a housing of the cassette in order toaccommodate relative movement of a capstan that is used to drive theuptake spool.